Thalidomide and its immune-modulatory analogue lenalidomide have clinical activity in myeloma. Pomalidomide, a thalidomide analogue, is an immunomodulatory agent that displays similar anti-angiogenic activity, but far greater anti-proliferative and immunomodulatory activity, compared to the parent drug. Pomalidomide and lenalidomide have been shown to possess very similar pharmacological properties in vitro, including anti-angiogenic, immunomodulatory and anti-proliferative properties. However a unifying molecular mechanism for these diverse effects has been elusive. Pomalidomide and lenalidomide have significantly greater capacity for enhanced costimulation, leading to enhanced activation of innate and adaptive immune cells compared to Thalidomide. Recent studies have yielded the surprising finding that these agents can mediate rapid biologic effects on human monocytes and T cells in culture leading to activation of ras homolog gene family, member A (RhoA) GTPases, and enhanced actin polymerization. Changes in actin cytoskeleton may also contribute to the capacity to these drugs to enhance the formation of immune synapses, Pomalidomide has also been shown to stimulate antibody-dependent cytotoxic T-cell activity (ADCC) in preclinical models.